Portable electronics devices tend to combine functionality with small size. But in order to add functionality, portable electronic devices tend to have to sacrifice compactness. Additional functionality typically requires additional user-interface features. A housing for an electronic device has to be sufficient in size in order to provide for the additional user-interface features. The housing may also have to be sufficient to provide for additional internal components needed for the added functionality.
Devices that combine to distinct functions are usually larger or more bulky than devices that provide the same functions individually. For example, hybrid devices exist that are both personal digital assistants (PDAs) and cellular phones. These devices tend to be larger than devices that are only cellular phones or PDAs. Part of the reason why hybrid devices are larger is that the device's PDA functionality require it to be large enough to provide user-interface features that include a contact-sensitive display, a set of buttons and a stylus. The cellular phone functionality requires sufficient housing space to support a numeric keypad, and an antenna. The user-interface features of the PDA and cellular phone functions do not overlap. Consequently, the housing has to be large enough to provide both.